1. Field of Invention
The invention relates to a fluid bearing module for rotating devices and, in particular, to a fluid bearing module that has the functions of preventing the lubricant medium from leaking and the deflecting member from getting loose.
2. Related Art
The bearings are used in rotating devices to provide support, to reduce friction, and to withstand loads. As modern devices are getting smaller and become compact, the precision requirement on the bearing is also getting higher. The most commonly used ball bearings thus have higher cost than before. For example, for the ball bearings used in motors, the cost is above one third of the total cost of the motor. Therefore, the cost for miniaturization is too high. Moreover, if the ball bearing has any defect, there will be such problems as high noises and insufficient precision during the operation of the rotating device. In particular, when the ball bearings are used in the optical disc drive motors, the instability caused by the bearings with low precision is likely to result in errors when the optical disc drive is reading a high density storage medium. As the ball bearings cannot simultaneously satisfy the requirements of miniaturization, high precision, and low cost, people have invented fluid bearings that can reduce rotational friction, have high precision, low noises, and are resistant to vibrations.
Generally speaking, in order not to let the lubricant medium leak out of the bearings, there are two designs: dynamical anti-leaking and static anti-leaking.
The dynamical anti-leaking design of the fluid bearings is to make a human-shape micro groove (see FIGS. 1 and 2). The micro groove is filled with a lubricant medium. When the fluid bearing is rotating, the lubricant medium inside the micro groove is driven to flow along the concave part of the micro groove. Therefore, during the rotation of the fluid bearing, the lubricant medium is limited to the concave part of the micro groove, serving it lubrication function. As the pressure on the central part of the fluid bearing is larger, it does not wiggle much and the lubricant medium does not flow out of the fluid bearing, either. The lubricant medium is thus sealed inside the fluid bearing. Therefore, the fluid bearings can be used in high-precision products. Moreover, as the lubricant medium is kept in the concave part of the micro groove, it has the advantages of reducing rotational friction, noises, and vibrations. They are ideal for the motors of information appliances, hard disc drives (HDD's) and optical disc drives
The static anti-leaking design of the fluid bearing is shown in FIG. 1. A gap L between the rotating device and the fluid bearing (about 2 to 16 micrometers) is employed so that under its static state the lubricant medium is kept between the rotating device and the fluid bearing through its surface tension. The smaller the gap is, the larger surface tension the lubricant medium has. Therefore, only high-precision products (such as HDD's) can use such a static anti-leaking design. When shipping low-precision products from one place to another for assembly, the lubricant medium is likely to flow out of the fluid bearing in this case. Besides, the lubricant medium can easily flow out of the fluid bearing when the product is placed up side down.
In addition, after assembling the rotating device and the fluid bearing, one has to rely on an anti-plug design so that the rotating device will not get loose during the shipping. Most of current designs fix the relation between the rotating device and the fluid bearing using an external mechanism after the rotating device and the fluid bearing are assembled. However, such a method involves very complicated element designs.